<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
 
  <button>Click me any way you want</button>
  <script>
    let button = document.querySelector("button");
    button.addEventListener("mousedown", event => {
      if (event.button == 0) {
        console.log("Left button");
      } else if (event.button == 1) {
        console.log("Middle button");
      } else if (event.button == 2) {
        console.log("Right button");
      }
    });
  </script>

</body>
</html>